Lead Full Stack Engineer at SpruceID

We're on a mission to make it simple and affordable for every home in the UK to be heated and powered by clean, green electricity. Our customers are the installers who are at the forefront of this transition, but who have historically been overlooked and left struggling with outdated, ineffectual software. Since getting started at beginning of 2024, we've grown exponentially, have raised several rounds of funding from top tier VCs, and now support over 700 heat pump installation businesses across the UK. We're looking for an exceptional Lead Engineer to help us move faster and go further as we start to expand outside heat pumps. Quick background on Spruce We've started with most challenging but ultimately most important part of the home energy transition: replacing boilers with heat pumps. Nearly 20% of the UK's carbon emissions come from heating homes. There is no credible path to net zero without replacing gas and oil boilers — and today, heat pumps are the only scalable alternative with their almost-magical ability to convert 1kW of electricity into 4kW of heat (🤯). The problem? The installation process is slow, fragmented, and painfully manual. This increases costs for homeowners, limits how fast installation businesses can grow, and makes it almost impossible to offer a heat pump when someone's boiler breaks down. We're fixing this. We've built an end-to-end operating system for heat pump installers — from initial enquiry through design and installation to compliance and paperwork. Relative to the best alternatives, Spruce now: Halves the time installers spend per job; Doubles sales conversion rates; and Improves quality, margins, and customer experience. And we're only just getting started. With fresh investment and growing demand, we're now expanding into the rest of the home renewables supply chain – supporting manufacturers and merchants as well as installers, and enabling solar & battery installations alongside heat pumps. The Role As a Lead Full Stack Engineer, you'll sit at the intersection of hands-on technical work, team leadership, and product strategy. You'll still write a bunch of code — especially the hard, high-leverage parts — but your impact will increasingly come from setting direction, unblocking others, and raising the bar across the team. You'll work closely with engineers, designers, and product leadership to ensure we're building the right things , in the right way , at the right time . What you'll do Own architecture and technical strategy for a core domain or set of systems. Design, guide, and build complex, cross-cutting solutions that span multiple parts of the product. Write high-leverage code: reference implementations, critical paths, foundational frameworks. Lead technical discussions, make trade-offs explicit, and help teams align. Mentor senior engineers and develop others into technical leaders. Coach engineers in how to make decisions, rather than making every decision yourself. Proactively identify sca